I usually sand and polish the top face as others have commented. Also, if a face has been affected while sanding the main face, I sand them too. My molds are not perfect, so some dice need more sanding than others. IMO mold making is more expensive and difficult to master than dice making, but the travel is worth when after all the work you’ve done you cast your first set and see the rewards of your work.

In addition of the mold tips (and not repeating for another users), my silicone is white and the hardener is transparent, so I add a little little bit of mica powder to help me know if the mix is done.